Quiescent Period Research Articles

Automated interpretation of the pulmonary function test by a portable spirometer in Chinese adults.

IntroductionA portable spirometer is a promising alternative to a traditional pulmonary function test (PFT) spirometer for respiratory function evaluation.ObjectivesThis study aimed to investigate the accuracy of automated interpretation of the PFT measured by a portable Yue Cloud spirometer in Chinese adults.MethodsThe PFT was performed to evaluate subjects prospectively enrolled at Ruijin Hospital (n = 220). A Yue Cloud spirometer and a conventional Jaeger MasterScreen device were applied to each patient with a 20‐min quiescent period between each measurement. Pulmonary function parameters, including forced vital capacity (FVC), forced expiratory volume in the first second (FEV1), peak expiratory flow (PEF), maximal expiratory flow at 25%, 50%, and 75% of the FVC (MEF25, MEF50, and MEF75, respectively), and maximal mid‐expiratory flow (MMEF), were compared by correlation analyses and Bland–Altman methods. The Yue Cloud spirometer automatically interpreted the PFT results, and a conventional strategy was performed to interpret the PFT results obtained by the Jaeger machine. Concordance of the categorization of pulmonary dysfunction, small airway dysfunction, and severity was analyzed by the kappa (κ) statistic.ResultsSignificantly similar correlations of all variables measured with the two spirometers were observed (all p < 0.001). No significant bias was observed in any of the measured spirometer variables. A satisfactory concordance of pulmonary function and severity classification was observed between the automated interpretation results obtained with the Yue Cloud spirometer vs. a conventional spirometer interpretation strategy (all κ > 0.80).ConclusionThe portable Yue Cloud spirometer not only yields reliable measurements of pulmonary function but also can automatically interpret the PFT results.

Pseudo-prospective forecasting of large earthquakes full distribution in circum-Pacific belt incorporating non-stationary modeling

The noticeable increase in the occurrence rate of the great (M≥8.0) global earthquakes since 2004, provokes the extensive investigation of non-stationarity in their temporal distribution. The reliable evaluation of their expected occurrence rates is a highly demanding aspect due to the co-existence of scarce long interevent times (extreme events) and localized clustering. In this work, we establish a two-step modeling procedure of the Markovian Arrival Process (MAP) to simultaneously forecast the occurrence of extreme events and short-term seismicity and we implement catalog-based pseudo-prospective forecasting experiments for the full distribution of the occurrence frequency. MAP model is a two-dimensional point process, whose intensity function is driven by a hidden Markov process, Jt. We adopt the existence of an “idle” state that corresponds to periods of relative seismic quiescence and its occurrence rate, λidle, is estimated a-priori, which is then embedded as a constant in the iterative fitting procedure of the MAP. We show the superiority of the MAP over renewal models and the temporal Epidemic Type Aftershock Sequence model, by producing robust probabilistic forecasts for the full temporal distribution of large earthquakes (M≥7.6) in circum-Pacific belt during 1918–2020, after considering a sensitivity analysis over both the testing periods and the magnitude thresholds.

More than a warning: Expanding the role of communication in Eastern Caribbean volcano science

The infrequent nature of volcanic eruptions means that civil authorities and the public may often be unfamiliar with volcanic hazards and may not be fully prepared to deal with them. Many times volcano scientists are required to help governments and citizens understand the threat posed to their lives and property when volcanoes show signs of an imminent eruption. Effectively communicating the potential impact of these events can demand time and skills that these scientists may or may not have. Further, a lack of trusted scientific information can lead to public misinformation and hamper government responses. Although several risk reduction researchers and observatory scientists have advocated for the inclusion of communication specialists in scientific teams, communication resources at many observatories remain under utilised. Using the experience of The University of the West Indies Seismic Research Centre (UWI-SRC), this article explores the contribution of a specialist communication team to the work of a volcano monitoring agency. The Education and Outreach (E&amp;amp;O) team at the UWI-SRC manages all the agency’s external communications. The team also works to raise public awareness of geological hazards in the UWI-SRC’s Eastern Caribbean region of responsibility. Within the Caribbean region, most communication research related to disaster risk up until now has focused on communication during crises. Using semi-structured interviews and document review we investigated the impact of strategic communication in a long-term, multi-hazard monitoring programme. A qualitative analysis highlighted the equal importance of crisis communication during unrest and outreach work during quiescent periods. The UWI-SRC’s communication programme has been effective in: 1) supporting scientists’ public communication 2) sustaining stakeholder engagement 3) building physical and social science capacity and 4) strengthening organisational credibility. This article examines the contribution of specialist communication to advisory volcano science throughout the disaster management cycle in the English-speaking Eastern Caribbean. It argues that significant societal value can be added to the scientific work engaged in by advisory scientists by embracing a multi-level communication strategy.

A millimeter-scale insight into formation mechanism of lacustrine black shale in tephra deposition background

To reveal the role of tephra in the deposition of black shale during periods of volcanic activity, we performed lithostratigraphic and geochemical analyses on 14 horizontally sliced samples drilled from a 2-cm-thick black shale interval in the lower Ch7 Member of the Upper Triassic Yanchang Formation, southern Ordos Basin. Results indicate that fewer plankton is preserved during tephra deposition than during periods of volcanic quiescence. With the decrease of volcanic activities and tephra deposition, the abundance of redox-sensitive trace elements (RSTEs) and biolimiting elements increases, while terrigenous elements gradually decrease, resulting in the improvement of organic matter (OM) preservation. Paleoenvironmental proxies suggest that the climate during the Late Triassic was generally warm and humid. However, subsequent intense volcanic eruptions may have caused climatic cooling that affected the water column, resulting in enhanced salinity, primary production, water stratification, and bottom water anoxia, leading to enhanced organic carbon production and preservation. Primary productivity and redox conditions controlled the accumulation of organic carbon. Although physical and chemical reactions relating to the deposition of tephra into water are short-lived, climate change induced by volcanic eruptions is the critical cause of black shale formation.

The high energy spectrum of Proxima Centauri simultaneously observed at X-ray and FUV wavelengths

The M dwarf Proxima Centauri, the Sun’s closest stellar neighbour, is known to be magnetically active and it hosts a likely Earth-like planet in its habitable zone. High-energy radiation from the host star can significantly alter planetary atmospheres in close orbits. Frequent flaring may drive radiation-induced effects such as rapid atmospheric escape and photochemical changes. Therefore, understanding the characteristics of stellar radiation by understanding the properties of the emitting plasma is of paramount importance for a proper assessment of the conditions on Proxima Centauri b and exoplanets around M dwarfs in general. This work determines the temperature structure of the coronal and transition region plasma of Proxima Centauri from simultaneous X-ray and far-ultraviolet (FUV) observations. The differential emission measure distribution (DEM) was constructed for flaring and quiescent periods by analysing optically thin X-ray and FUV emission lines. Four X-ray observations of Proxima Centauri were conducted by the LETGS instrument on board of the Chandra X-ray Observatory and four FUV observations were carried out using the STIS spectrograph on board the Hubble Space Telescope. From the X-ray light curves, we determined a variation of the quiescent count rate by a factor of two within 20% of the stellar rotation period. To obtain the DEM, 18 optically thin emission lines were analysed (12 X-ray and six FUV). The flare fluxes differ from the quiescence fluxes by factors of 4–20 (FUV) and 1–30 (X-ray). The temperature structure of the stellar corona and transition region was determined for both the quiescence and flaring state by fitting the DEM(T) with Chebyshev polynomials for a temperature range log T = 4.25–8. Compared to quiescence, the emission measure increases during flares for temperatures below 0.3 MK (FUV dominated region) and beyond 3.6 MK (X-ray dominated region). The reconstructed DEM shape provides acceptable line flux predictions compared to the measured values. Using the DEM we provide synthetic spectra at 1–1700 Å, which may be considered as representative for the high-energy irradiation of Proxima Cen b during quiescent and flare periods. In future work these values can be used for planet atmosphere calculations which will ultimately provide information about how habitable Proxima Centauri b is.

Alpine rock glacier activity over Holocene to modern timescales (western French Alps)

Abstract. Active rock glaciers are some of the most frequent cryospheric landforms in midlatitude high-elevation mountain ranges. Their activity strongly influences the hydrology and geomorphology of alpine environments over short (years to decades) and long (centuries to millennia) timescales. Being conspicuous expressions of mountain permafrost and important water reserves in the form of ground ice, rock glaciers are seen as increasingly important actors in the geomorphological and hydrological evolution of mountain systems, especially in the context of current climate change. Over geological timescales, rock glaciers both reflect paleoclimate conditions and transport rock boulders produced by headwall erosion, and they therefore participate in shaping high mountain slopes. However, the dynamics of rock glaciers and their evolution over different timescales remain under-constrained. In this study, we adopt a multi-method approach, including field observations, remote sensing, and geochronology, to investigate the rock glacier system of the Vallon de la Route (Combeynot Massif, western French Alps). Remotely sensed images and correlation techniques are used to document the displacement field of the rock glacier over timescales ranging from days to decades. Additionally, to estimate displacement over periods from centuries to millennia, we employ terrestrial cosmogenic nuclide (quartz 10Be) surface-exposure dating on rock boulder surfaces located along the central flow line of the rock glacier, targeting different longitudinal positions from the headwall to the rock glacier terminus. The remote sensing analysis demonstrates that between 1960 and 2018 the two lower units of the rock glacier were motionless, the transitional unit presented an integrated surface velocity of 0.03±0.02 m a−1, and the two upper active units above 2600 m a.s.l. showed a velocity between 0.14±0.08 and 0.15±0.05 m a−1. Our results show 10Be surface-exposure ages ranging from 13.10±0.51 to 1.88±0.14 ka. The spatial distribution of dated rock glacier boulders reveals a first-order inverse correlation between 10Be surface-exposure age and elevation and a positive correlation with horizontal distance to the headwall. These observations support the hypothesis of rock boulders falling from the headwall and remaining on the glacier surface as they are transported down valley, and they may therefore be used to estimate rock glacier surface velocity over geological timescales. Our results also suggest that the rock glacier is characterized by two major phases of activity. The first phase, starting around 12 ka, displays a 10Be age gradient with a rock glacier surface velocity of about 0.45 m a−1, following a quiescent period between ca. 6.2 and 3.4 ka before the emplacement of the present-day upper two active units. Climatic conditions have favored an integrated rock glacier motion of around 0.18 m a−1 between 3.4 ka and present day. These results allow us to quantify back-wearing rates of the headwall of between 1.0 and 2.5 mm a−1, higher than catchment-integrated denudation rates estimated over millennial timescales. This suggests that the rock glacier system promotes the maintenance of high rock wall erosion by acting as debris conveyor and allowing freshly exposed bedrock surfaces to be affected by erosion processes.

Tectonostratigraphic evolution of the Sohar Basin, exploration concepts and emerging plays offshore on the UAE's east coast

The Sohar Basin, located offshore the East Coast of the Arabian Peninsula, is an area that has seldom been the focus of international oil companies. While all commercial discoveries in the UAE and Oman have been made to the west and south of the Oman Mountains, the Sohar Basin is underexplored and remains prospective. This lack of activity is primarily because the Thamama reservoir, which has yielded huge success to the west of the Oman Mountains is likely not present within the Sohar Basin. However, potential traps, reservoirs, and source rocks are present within the Tertiary succession. The Sohar Basin formed in the late Cretaceous after the obduction of the Semail Ophiolite onto the Arabian Plate. Following a period of tectonic quiescence, which lasted until the Early Eocene, the gravitational collapse occurred along the eastern edge of the present-day Oman Mountains.Interpretation of both 2D and 3D seismic reveals that the subsurface is comprised of three tectonostratigraphic units, defined as pre-, syn-, and post-tectonic packages. North-South trending thrust faults generate distinct mini-basins within the pre- and syn-tectonic sequences. The post-tectonic sequence is defined by the development of prograding systems in a tectonically quiescent margin formed in the Lower Miocene and which persists to the present day. Deep-water depositional systems dominate the undrilled far-east and south of the basin where the presence of submarine canyon systems and associated basin floor fans is supported by 3D seismic data. In recent times, the Sohar Basin has been subject to extensional faulting likely driven by sediment load caused by a prograding delta system.The results of this work reveal that multiple untested play types exist within the Sohar Basin, which are comprised of both structural and stratigraphic elements. This paper integrates both a structural and sequence stratigraphic interpretation to provide insights into the tectonostratigraphic evolution of the Sohar Basin. Consequently, the fundamentals of play fairway mapping have been employed to unlock the hydrocarbon prospectivity offshore the UAE's East Coast.

Influence of environmental factors and body condition on the post-oviposition behavior in the emerald glass frog Espadarana prosoblepon (Centrolenidae).

In species with parental care behaviors, parents may adjust the intensity and duration of their care if fluctuation in factors such as environmental variables or body condition affects offspring survival. In the face of environmental changes, many egg-laying species remain with their clutch for extended periods if this behavioral adjustment provides tangible benefits to the offspring. However, the length of time parents stay with the offspring may also differ depending on the individual’s body condition. In the glass frog family (Centrolenidae), several species exhibit long-term egg attendance in which they remain with their clutch for several days after oviposition takes place. For some of them, changes in environmental variables lead to increased parental care efforts. For the species in which parents remain with their offspring for a short period (less than 24 hours), it is less clear if this constitutes parenting behavior, and whether parents adjust their efforts as a function of environmental change or the parent’s body condition remains unexplored. We studied a population of the Emerald Glass Frog, Espadarana prosoblepon, a species that exhibits a short period of quiescence after oviposition (less than three hours). Our study aimed to determine whether females alter the length of their post-oviposition quiescence period in response to changes in environmental variables (i.e., temperature, humidity, rainfall, and mean wind speed) or female body condition. Pairs in amplexus were captured in the field and transported to semi-natural enclosures to record the duration of post-oviposition quiescence using infrared cameras. Females’ post-oviposition quiescence lasted an average of 67.4 ± 26.6 min (range = 22.7–158.3 min). We did not find a significant relationship between the duration of the post-oviposition quiescence and any of the environmental variables tested. Similarly, post-oviposition quiescence duration was not influenced by female body condition. Because the variation observed in the duration of post-oviposition quiescence was not related to changes in extrinsic (environmental) or intrinsic (body condition) factors, we found no evidence that females of E. prosoblepon modify their post-oviposition behavior in response to any of the variables examined in this study. Future research investigating the adaptive significance of the post-oviposition quiescence observed in this species is needed to understand how this behavior is related to parental care efforts.

Computational simulations and Ca2+ imaging reveal that slow synaptic depolarizations (slow EPSPs) inhibit fast EPSP evoked action potentials for most of their time course in enteric neurons.

Transmission between neurons in the extensive enteric neural networks of the gut involves synaptic potentials with vastly different time courses and underlying conductances. Most enteric neurons exhibit fast excitatory post-synaptic potentials (EPSPs) lasting 20-50 ms, but many also exhibit slow EPSPs that last up to 100 s. When large enough, slow EPSPs excite action potentials at the start of the slow depolarization, but how they affect action potentials evoked by fast EPSPs is unknown. Furthermore, two other sources of synaptic depolarization probably occur in enteric circuits, activated via GABAA or GABAC receptors; how these interact with other synaptic depolarizations is also unclear. We built a compartmental model of enteric neurons incorporating realistic voltage-dependent ion channels, then simulated fast EPSPs, slow EPSPs and GABAA or GABAC ligand-gated Cl- channels to explore these interactions. Model predictions were tested by imaging Ca2+ transients in myenteric neurons ex vivo as an indicator of their activity during synaptic interactions. The model could mimic firing of myenteric neurons in mouse colon evoked by depolarizing current during intracellular recording and the fast and slow EPSPs in these neurons. Subthreshold fast EPSPs evoked spikes during the rising phase of a slow EPSP, but suprathreshold fast EPSPs could not evoke spikes later in a slow EPSP. This predicted inhibition was confirmed by Ca2+ imaging in which stimuli that evoke slow EPSPs suppressed activity evoked by fast EPSPs in many myenteric neurons. The model also predicted that synchronous activation of GABAA receptors and fast EPSPs potentiated firing evoked by the latter, while synchronous activation of GABAC receptors with fast EPSPs, potentiated firing and then suppressed it. The results reveal that so-called slow EPSPs have a biphasic effect being likely to suppress fast EPSP evoked firing over very long periods, perhaps accounting for prolonged quiescent periods seen in enteric motor patterns.

The ∼2.3 Ga magmatic event in tectonic quiescent period: Geochronological and geochemical constraints from the Xiaohe granite in the Xiaoqinling Terrane at southern North China Craton

The early Paleoproterozic is generally considered as a worldwide tectonic quiescent period. It is unusual that widespread early Paleoproterozoic magmatism has been identified in the North China Craton (NCC), especially in the Xiaoqinling Terrane at the southern NCC. The Xiaohe granite occurs along the southern margin of the Xiaoqinling Terrane and intrudes the lower portion of the Taihua Supergroup (gneisses). Previous data suggest the emplacement time of the Xiaohe granite ranging from the early to late Paleoproterozoic, leaving a controversy over 500 Ma. To accurately constrain the age, genesis and tectonic setting of the Xiao granite, we have carried out a comprehensive study and here present new petrographical, geochronological, and isotope and element geochemical data. It is confirmed that the Xiaohe granite is dominated by the ca. 2.3-Ga monzogranite and locally intruded by the Guijiayu granites at 1.82 ± 0.05 Ga. Three samples from the Xiaohe granite yield consistent zircon U − Pb ages of ca. 2.3 Ga, and ɛHf(t) values showing mixing of juvenile and recycled continental crust sources. The Xiaohe granite are characterized by high SiO2 (70.7–79.6 %) and high alkali (5.67–10.15 %), belong to calc-alkaline to shoshonite series and show weak peraluminous feature with A/CNK values around 1.1. Its geochemical characteristics are similar to those of A-type granites formed involcani arc or syn- to post-collision tectonic settings. Samples also display eastward decrease of Sr/Y, (La/Yb)N and δEu values, and weakening REE fractionation, indicating an eastward increase of plagioclase in residue during partial melting of the crust, and the magma sources become shallow eastwardly. Hence it is concluded that the Xiaohe granite was formed in a widespread granitic event associated with continental collision or terrane amalgamation.

THE DESIGN AND HYDRODYNAMIC ASSESSMENT OF A SUBMARINE CONCEPT WITH OFF-AXIS RESOLVING THE IMPACT OF SHIP’S DESIGN ON DECK AND WELL-DECK LAUNCH AND RECOVERY OPERATIONS BY APPLYING OF QUIESCENT PERIOD PREDICTION (QPP)

One of the most challenging tasks in the deployment of ship-based manned and unmanned VTOL aviation is the launch and recovery and deck handling operational performance on smaller ship platforms. The same may be said of ship Well-deck-based surface boats, like Rhib and LCACs. Awareness and prediction of the ship’s position and movement in the ocean is key to ship-based air operations by targeting the right time to deploy and recover. The ships above waterline design coupled by the propulsion systems, affects ship’s motion and ship motion induced air wake behaviour. MoD/University of Exeter’s Quiescent Period Prediction (QPP) Program Aims to deliver technologies which support launch and recovery from Naval assets, particularly in higher sea states. The Quiescent Period Prediction (QPP) system achieves this by using a wave sensor system to measure the sea surface several hundred meters in advance of the ship. From the measured sea surface, a short-term deterministic wave model can be constructed allowing the wave system to be propagated to the ship's location. The ship's response to the wave spectrum is calculated to determine the level of quiescence at the time of encounter. The results are mapped dynamically on speed-polar visual graphics providing the ship’s best course to steer to ensure encountering the quiescent zone in a timely manner. The ability to fully define a ship’s motion as a function of a recovery device, greatly enhances the overall system operational capability whilst fundamentally reducing the inherent risks associated with platform manipulation in high sea conditions. The use of simulation, routinely considered in the UK, as an alternative to traditional approaches such as scale model testing and fullscale sea trials, to predict the safety and performance envelopes of platforms and systems, is discussed. Operating over deck whilst the ship is experiencing a quiescent period normally has the secondary effect of reduced air wake confusion. This is owing to fewer ship structure excursions into and out of the air flow. To better define off deck airflow around the ship a future QPP improvement will be the development and installation of a Doppler LiDAR federate. The objective of this work is to define ship-helicopter operational deck limits (SHOL), and then to safely expand ship operating deck limits. This article discusses the background to aircraft/ship operations in relation to QPP and goes on to consider both short term implementations (the Landing Period Designator System) and longer horizon deterministically predictive forms of QPP. This article describes the development of the QPP System concentrating on test procedures, timely seaway mapping and ship motion characteristics to complete specific motion sensitive task. An overview of the theory and application is provided concerning dynamic interface analysis with the focus on encountered forces and vehicle to platform response stability.

The spectral analysis and study of GRB 120709A, a burst with three distinct emission episodes

The reason for quiescent intervals and isolated emission episodes in gamma-ray burst (GRB) light curves is still not well understood. Probing these questions further requires the study of the spectral characteristics and properties of the outflow of such GRBs. GRB 120709A is a burst with three distinct emission episodes, separated by quiescent periods lasting several seconds. The episodes are comparable with each other in terms of peak flux and duration. The GRB was observed by the Fermi LAT and GBM instruments, covering over six orders of magnitude of energy. In this work, we carry out the time-integrated and time-resolved spectral analysis of GRB 120709A. We use these results to study the temporal variation of its parameters. In particular, we find that the peak energy of the spectrum of each episode traces the flux of those episodes. We also study and parameterise the correlation between the isotropic luminosity and intrinsic peak energy. Finally, we determine the parameters of the outflow based on gamma-gamma opacity calculations. We find that if we require the MeV emission to occur above the photosphere, then the ratio of the GeV and MeV emission radii can not be greater than ∼1.2. This implies an internal origin of the GeV emission. This also allows us to estimate the average value of the Lorentz factor to be in the ∼100–200 range. We also evaluate the photospheric and MeV emission radii and find them to be in the (4.5–5.3) ×1012 cm and (2.1–5.2) ×1014 cm ranges, respectively. We note the limitations of this exercise due to the relative faintness of the GRB which prevents us from doing a very fine time-resolved analysis or fitting the spectra with multi-component models. We also discuss GRB 120709A in the context of models for distinct emission episodes and quiescent intervals.

LGG-58. Understanding the transcriptional heterogeneity of pediatric low-grade gliomas and its implication for tumor pathophysiology

Pediatric low-grade gliomas (pLGGs) are the most frequent brain tumors in children and comprise a heterogeneous group of tumors with different locations, histologic subtypes, ages at presentation, and clinical behavior. Tumors frequently respond to treatment with chemotherapy or surgical removal, but they can regrow after a period of quiescence, requiring further therapy. Thus, a deeper understanding of the molecular processes involved in these tumors is required to develop therapeutic strategies that are effective against their disease mechanisms. To better understand the cellular behaviors of this heterogenous group of tumors, we have employed single-cell and single-nuclei RNA sequencing technologies to analyze a large-scale dataset (>250,000 cells) of pLGGs. Analysis of this data identified a heterogenous population of cell types and cell states, detecting mature and progenitor-like astrocytes and oligodendrocytes, as well as cells exhibiting senescence or cycling programs. Moreover, we identify a significant immune infiltrate, comprised primarily of microglia. In addition to heterogeneity within pLGG tumors, heterogeneity between LGG subtypes represents another layer that stratifies pLGG biology. We performed a compositional analysis of the cell types present in these tumors and compared transcription signatures and gene expression programs across shared cellular populations of histologically and genetically distinct pLGGs. Finally, we optimized our integration and batch correction analyses by using external 293T cells as spike in controls during our single-cell and single-nuclei data generation steps to determine the most suitable method for batch-effect removal. Our analysis of human pLGGs at the single-cell and single-nuclei resolution provides critical insight into the heterogenous biological activities that constitute these tumors.

Investigating apatite (U-Th)/He thermochronologic ages to understand exhumation history of the Ethiopian Plateau

Although the Ethiopian Plateau is a prominent feature in East Africa, its exhumation history is not well constrained. For the last few decades, this history has been a topic of scientific interest due to the plateau's complicated geologic setting and thermal response to surface topographic changes. Studies of the plateau's thermal history have the potential to cast light on the numerous tectonic and geodynamic events that have affected the region since the beginning of the Mesozoic, such as Gondwana rifting, Afar mantle plume upwelling, continental flood basalt emplacement, Cenozoic continental rifting, and shield and cinder cone volcanism that has continued until the present day. We present new single-grain apatite (U-Th)/He (AHe) thermochronologic cooling ages from the Blue Nile Canyon to address the Ethiopian Plateau's exhumation history. AHe dates of 55 grains from nine Neoproterozoic basement and Mesozoic sedimentary rock samples, collected from a vertical transect of the Blue Nile Canyon, range from 58.9 ± 2.7 to 460.2 ± 34.7 Ma. Interpretation of these cooling ages is complex due to intra-sample age dispersion. We address this dispersion by systematically evaluating the ages based on standard deviation percentage, effective Uranium concentration [eU], and equivalent spherical grain radius r, which also helps select samples to generate a geologically meaningful thermal history model. Our inverse thermal history model using the Radiation Damage Accumulation and Annealing Model (RDAAM) reveals a protracted Paleozoic cooling, a gradual reheating during Permo-Mesozoic time (between ∼300 and ∼100 Ma), and a rapid cooling in the Cretaceous (∼100 Ma). This Paleozoic and Mesozoic thermal history reflects post-Pan-African orogenic denudation followed by Gondwana rift-related burial and then exhumation. A period of tectonic quiescence is reflected between ∼100 and ∼30 Ma, during which there was little to no cooling. Although our thermal model shows burial-related reheating after the flood basalt emplacement around 30 Ma and eventual cooling to present-day surface temperature, our thermochronologic data likely lack sufficient resolution to determine the details of the Neogene cooling related to incision of the Blue Nile Canyon. Our study suggests that the thermal history of the Ethiopian Plateau is dynamic and warrants further high-resolution, low-temperature thermochronologic investigation to constrain post-30 Ma river incision of the plateau.

Re-examination of the Base Miocene Unconformity in west Sabah, Malaysia, and stratigraphic evidence against a slab-pull subduction model

This review chiefly examines data on the regionally important Base Miocene Unconformity , confirming its age and expression in west Sabah, then integrates this with data on the tectono-stratigraphic development of the broader Sabah to Palawan region. The two unconformities described (the Base Miocene Unconformity and the younger Deep Regional Unconformity) were both produced when deformation abruptly stopped, leaving erosional surfaces that were then transgressed. The ages of these two events are c. 24 and 12–13 Ma respectively, and the areas affected by the prior uplift and erosion can be mapped. The results are incompatible with widely cited plate tectonic models that describe closure of a postulated Proto-South China Sea [PSCS]. These prior models had assumed plate drift ended with collision at plate docking over a PSCS suture in about mid Early Miocene times. However, stratigraphic data shows that Early Miocene times were a period of quiescence across Sabah, with mostly mild subsidence . It is therefore proposed that plate drift in the SCS could not have been linked to any type of subduction process anywhere around western Sabah. The absence of any plate docking or any Oligocene through Middle Miocene compression around northern Palawan is a further anomaly to the old subduction based tectonic model.

Simultaneous bilateral inflammatory choroidal neovascularization in a case of healed serpiginous-like choroiditis.

Objective: Inflammatory choroidal neovascularization (i-CNV) is an infrequent but sight-threatening complication of posterior uveitis. Although it can occur in a wide range of infectious and non-infectious uveitides, presence of simultaneous bilateral i-CNV is rare. In this report, we present a unique case of bilateral simultaneous i-CNV in a young patient of healed tubercular serpiginous-like choroiditis.Method: A 20-year-old male presented with recent worsening of vision in the right eye for one month. Fundus examination revealed bilateral multifocal healed choroiditis lesions with right eye tiny subfoveal hemorrhage raising the suspicion of an underlying choroidal neovascularization. Fundus fluorescein angiography and optical coherence tomography confirmed presence of choroidal neovascular membrane in both eyes.Result:Resolution of activity was noted in both eyes after bilateral sequential intravitreal bevacizumab injections.Conclusion:Inflammatory choroidal neovascularization may be seen in patients with healed tubercular serpiginous-like choroiditis, after a long period of quiescence. Simultaneous bilateral presentation is rare but possible, requiring mandatory multimodal imaging of both eyes under high index of suspicion. Early institution of anti-vascular endothelial growth factor may salvage optimum vision in such a scenario.

Reducing MCPA herbicide pollution at catchment scale using an agri-environmental scheme

In river catchments used as drinking water sources, high pesticide concentrations in abstracted waters require an expensive treatment step prior to supply. The acid herbicide 2-methyl-4-chlorophenoxyacetic acid (MCPA) is particularly problematic as it is highly mobile in the soil-water environment following application. Here, an agri-environmental scheme (AES) was introduced to a large-scale catchment (384 km2) to potentially reduce the burden of pesticides in the water treatment process. The main measure offered was contractor application of glyphosate by weed wiping as a substitute for boom spraying of MCPA, supported by educational and advisory activities. A combined innovation applied in the assessment was, i) a full before-after-control-impact (BACI) framework over four peak application seasons (April to October 2018 to 2021) where a neighbouring catchment (386 km2) did not have an AES and, ii) an enhanced monitoring approach where river discharge and MCPA concentrations were measured synchronously in each catchment. During peak application periods the sample resolution was every 7 h, and daily during quiescent winter periods. This sampling approach enabled flow- and time-weighted concentrations to be established, and a detailed record of export loads. These loads were up to 0.242 kg km−2 yr−1, and over an order of magnitude higher than previously reported in the literature. Despite this, and accounting for inter-annual and seasonal variations in river discharges, the AES catchment indicated a reduction in both flow- and time-weighted MCPA concentration of up to 21% and 24%, respectively, compared to the control catchment. No pollution swapping was detected. Nevertheless, the percentage of MCPA occurrences above a 0.1 μg L−1 threshold did not reduce and so the need for treatment was not fully resolved. Although the work highlights the advantages of catchment management approaches for pollution reduction in source water catchments, it also indicates that maximising participation will be essential for future AES.

Abstract B018: Targeting Notch4 and HIF2α signaling reduces the ability of cells to survive chemotherapy by undergoing the polyaneuploid transition

Abstract Giant cancer cells have been ignored for 200 years, but recently coupled to a role in metastasis and therapeutic resistance. Some cancer cells appear to survive environmental stress, such as chemotherapy or radiotherapy, via a polyaneuploid transition. This results in a PolyAneuploid Cancer Cell (PACC) state with up to 10-fold larger cell sizes. It is proposed that PACCs utilize a conserved evolutionarily or developmental program for polyploidization, which is commonly observed in other organisms and tissues. After a stress-induced formation, the PACC state first undergoes a period of quiescence and eventually undergoes reductive cell division to give rise to proliferative progeny. We hypothesize that PACCs play a role in tumor recurrence and therapy resistance by surviving the initial treatment and subsequently reseeding the tumor via pseudohypoxic HIF signaling. Dosing with LD50 cisplatin for 72h results in the induction of the PACC state in cancer cell lines from breast (HCC1806), renal (786-0), colon (HCT116), and lung (U1690) tumors. Cells in the PACC state had 3-fold larger nuclei after 3 days of treatment and 6-fold larger nuclei after 10 days. Transcriptomic data showed an overall decrease in gene expression across all 4 cell lines. However, there was an increased expression of HIF2 (2.7-fold), Notch4 (2-fold), Plekhs1 (2.3-fold) in PACCs relative to untreated control. Moreover, there was an increase in the expression of replication dependent histones. Overall, ATACseq indicated a reduction in open chromatin in PACCs, as measured by reduced levels of histone 4 and histone 4 modifications (H4k5ac, h4k16ac, H4R3me2). However, H3k27me3 was increased 20% and AP1 binding sites were enriched in open chromatin regions. HIF2 and AP1 cooperate to regulate gene expression and confer therapy resistance. We hypothesize that AP1 is activated in response to treatment and stabilizes HIF2 under oxygenated conditions. HIFs regulate regulators of the cell cycle to induce polyploidy and downregulate β-catenin, a known inducer of cytokinesis. Small molecule inhibition of Notch and HIF-2α reduced PACC formation by 50% and 65% respectively at day 3 and 60% and 75% at day 10. The surviving PACCs were smaller than those untreated by Notch and HIF-2α inhibitors. Large metabolic changes must be undertaken to generate and sustain the larger cellular mass accompanied by polyploidy. HIF signaling metabolically rewires cells to a glycolytic phenotype that provides a carbon source for increased de novo generation of nucleotides, lipids, and proteins. Indicative of this rewiring is that PACCs have increased expression of Hexokinase (2.5-fold), CPT1 (2.3-fold), and GP6D (2-fold). In conclusion, tumor cells that survive chemotherapy are polyaneuploid, larger, and in an altered metabolic state. This process appears driven by Notch4 and HIF-2α signaling. Combining conventional chemotherapy with Notch or HIF2α inhibitors presents an opportunity to reduce tumor recurrence by inhibiting a survival mechanism. Citation Format: Christopher P. Carroll, Emma Hammarlund, Kenneth J. Pienta, Sarah R. Amend. Targeting Notch4 and HIF2α signaling reduces the ability of cells to survive chemotherapy by undergoing the polyaneuploid transition [abstract]. In: Proceedings of the AACR Special Conference on the Evolutionary Dynamics in Carcinogenesis and Response to Therapy; 2022 Mar 14-17. Philadelphia (PA): AACR; Cancer Res 2022;82(10 Suppl):Abstract nr B018.

Integrated Quadrant Analysis: A New Method for Analyzing Turbulent Coherent Structures

Integrated quadrant analysis is a novel technique to identify and to characterize the trajectory and strength of turbulent coherent structures in the atmospheric surface layer. By integrating the three-dimensional velocity field characterized by traditional quadrant analysis with respect to time, the trajectory history of individual coherent structures can be preserved with Eulerian turbulence measurements. We develop a method to identify the ejection phase of coherent structures based on turbulence kinetic energy (TKE). Identifying coherent structures within a time series using TKE performs better than identifying them with the streamwise and vertical velocity components because some coherent structures are dominated by the cross-stream velocity component as they pass the sensor. By combining this identification method with the integrated quadrant analysis, one can animate or plot the trajectory of individual coherent structures from high-frequency velocity measurements. This procedure links a coherent ejection with the subsequent sweep and quiescent period in time to visualize and quantify the strength and the duration of a coherent structure. We develop and verify the method of integrated quadrant analysis with data from two field studies: the Eclipse Boundary Layer Experiment (EBLE) in Corvallis, Oregon in August 2017 (grass field) and the Vertical Cherry Array Experiment (VACE) in Linden, California in November 2019 (cherry orchard). The combined TKE identification method and integrated quadrant analysis are promising additions to conditional sampling techniques and coherent structure characterization because the identify coherent structures and couple the sweep and ejection components in space. In an orchard (VACE), integrated quadrant analysis verifies each coherent structure is dominated by a sweep. Conversely, above the roughness sublayer (EBLE), each coherent structure is dominated by an ejection.

Development and passive exhumation of high-pressure shear zones (Blueschist Unit, Syros): Insights from quartz and columnar calcite microstructures

Quartz and columnar calcite microstructures in two major high-pressure (HP) shear zones (Syros Island, Greece), which carry meta-igneous rocks over calcite marbles, were studied to investigate the deformation conditions associated with their development and exhumation. Quartz-rich bands within the hanging-wall of the shear zones record the deformation during the operation of the shear zones under HP conditions at slightly decreasing temperatures (from 500 °C to 450 °C). At HP conditions, the shear zones are associated with (E)SE-directed shearing under plane strain conditions, as well as with a temporal increase in strain rate of one order of magnitude (from ∼10−12 to ∼10−11). Well-preserved columnar calcite within marbles of the footwall indicates that ductile shearing along the shear zones should have abruptly ceased during the early stages of exhumation, passing to a period of relative quiescence within the stability field of aragonite at temperatures ∼430–450 °C. Progressive exhumation and cooling below 400 °C are associated with weak and distributed (E)NE-directed shearing with strain rate slower than ∼10−14. Our results from north(east) Syros indicate a change in transport direction from (W)NW-(E)SE at the deep subduction levels to (W)SW-(E)NE during exhumation. This change is linked to a change in deformation, from localized to weak and distributed revealing that the Blueschist Unit in north(east) Syros was exhumed as a nearly rigid body.